AllJackedUpF1504X4

Hey guys i have a 2002 f150 with the 5.4 with a misfire in cylinder 7 i changed the plug, the coil pack and injector and its still misfiring I dont know what to do. It idles rough and has no ***** when i accelerate. My check engine light flashes. I am getting codes P0307 and P0316. I had a misfire in a different cylinder last week. I changed all the plugs and a few coil packs last year when i had this problem. I dont know what else to do I need help thanks.

AFSOCSGT

Are you buying cheap coils??

roush360r

do you have a test light? if not go buy one. there cheap should be able to find one for like 10$. but hook the lead to ground side of batt with the key on and unplug the coil and injector. then check both the coil conector and injector conector. they should each have one wire that has power with the key on. next step if both the connectors have one wire with power is to put the lead on the pos side of the batt. now test the other wire in each connector. youll need someone to crank over the engine. the light should flash as it runs since the pcm controls ground.

AllJackedUpF1504X4

no i didnt buy cheap coil i bought them straight from napa they were good all summer no as soon as the snow has been flying i have had this problem. I will try the test light thing too

roush360r

well it could still be the coil. i have had problems with a variety of napa parts before. if everything tests good with the test light swap the napa coil with another coil from a different cyl and see if the misfire moves.

Deadeyemagnum

I agree. I tried to upgrade my ignition system with Accell coils. I immediately had a misfire that simply jumped from one cylinder to the next. In the end, I went back to the original Ford product and have had no problems since then.

offroadatv6

I had the same problem on cylinder one i was pulling a trailer and i was getiing on the highway and i jumped on it and about a quarter mile later the engine light started flashing and my truck ran like **** for about 15 seconds and then went away so i continued for about 2 hours on my trip and i hit a big hill so i got a run at it and about halfway up the hill it happened again... i took it to the shop the next day and they told me it was a cylinder 1 misfire so the guy switched cylinder one coil with cylinder 2 coil to basically check if it is the coil and the light hasn't come on again so I'm kind of lost cause I don't want to get stranded ... i was told that it might be the injector if its not the coil ... so thank you for any help

Good old Bill

Was wondering if you did a compression check when the plug was removed?

sharkbait

check for water or moister in the spark plug holes and try some dye electric grease or whatevers in those packets at the store. It really helps

AllJackedUpF1504X4

I always use dielectric grease when i do anything electrical. i did a compression test and it was not good only 25 psi and i tried again and got 0. i looked at my plug and noticed it looks like its blowin by the plug so i am guessing a have a serious problem with my threads. I have a friend of the family that owns a garage and use to work for FORD so he is going to look at it and let me know. I will tell you guys how i made out. thanks for the help tho